Advances in miniaturization of semiconductor devices have led to better performance and increased storage capacity for many electronic devices. Many process steps are involved in the manufacturing of semiconductor devices. One step is the doping of semiconductor substrate to form source/drain junctions. Ion-implantation is used to modify the electrical characteristics of the semiconductor substrate by the implantation of specific dopant impurities into the semiconductor wafer surface. The dopants that are commonly used are Boron, Arsenic, and Phosphorus. With the use of ion-implantation, a post annealing treatment is desired to complete the activation process and repair any associated damage to the implanted region. Various annealing techniques may be used, depending on the implant dosage (amount of atoms implanted in the surface) and the implant energy (depth of atoms into the surface). For example, annealing techniques may include furnace processing, Rapid Thermal Processing (RTP), Millisecond Anneal (MSA) and various other versions including laser annealing. However, there are disadvantages associated with each of these techniques, as described in U.S. Pat. No. 7,928,021, incorporated by referenced herein in its entirety.
Experiments using microwave heating for this annealing process have been performed within the solid state device industry, but use of microwave heating suffers from a number of disadvantages. For microwave heating, a multi-mode reaction chamber is used to heat/process a target substrate relatively larger than the wavelength of the microwave used. Within a multi-mode chamber, the microwave energy couples through mode excitation to govern the local microwave field, also referred to as an E-field. The E-field can also be influenced by the dielectric properties of the target substrate being heated inside the multi-mode chamber. Microwaves will flow in higher concentrations to the target substrate if it is made of a material with proper dielectrics. Based on the electromagnetic property of the microwaves and the skin effect of the target substrate within the multi-mode chamber, the target substrate may form a flow of current therethrough or on its surface based on its conductivity.
Unfortunately, E-field concentration can be difficult to monitor and control. For example, if the concentration of the E-field is strong enough, it can cause undesired thermal runaway and arcing independent of the microwave dielectric reaction, which can cause non-uniform heating and potential damage to the target substrate within the multi-mode reaction chamber. Stirrers and rotation plates have been used to attempt to make the E-field more uniform and metal foil layers have also been used to change the field energy locally to the target substrate being heated. However, each of these methods faces a challenge of trying to manage, minimize, or eliminate the formation of eddy currents to avoid uneven heating traditionally caused thereby.
Another method to heat the target substrate is a parallel plate reactor, most commonly used with radio frequencies (RF), mainly due to technical limitations at higher frequencies. Thus, the independent parallel plate reactor is generally limited to frequencies in the RF band and creates a limited reaction in the target substrate due to the wavelength used. RF heating in the prior art has only been introduced to the solid state market as a bulk heater, with no real difference in heating as compared to other traditional heating methods such as infrared and the like.